frighten the daylights out of
frighten the (living) daylights out of (someone)
To shock or frighten someone very suddenly and/or severely. Don't sneak up on me like that; you frightened the living daylights out of me!
frighten (or scare) the (living) daylights out ofgive someone a very severe fright.
This expression was a mid 20th-century development from beat the living daylights out of , on the premise that the effect of extreme fear is as drastic as physical violence.
1955 Frank Yerby The Treasure of Pleasant Valley Didn't mean to hit him…Meant to throw close to him and scare the living daylights out of him.